Melanoma, a malignant tumor, develops from abnormal melanocytes in the lower epidermis and can metastasize to distant sites in the body via the blood and lymph systems. Although it accounts for less than 5% of skin cancer cases, melanoma is much more dangerous and responsible for a large majority of the deaths associated with skin cancer. Across the world the incidence of melanoma has been increasing at an alarming rate, with a lifetime risk of developing melanoma as high as 1/58 for males in the U.S. (Jemal et al., 2008, CA: Cancer J. Clin. 58:71-96). The mortality rate of malignant melanoma also continues to rise dramatically throughout the world. According to a 2006 WHO report, about 48,000 melanoma related deaths occur worldwide per year (Lucas et al. (2006) Environmental Burden of Disease Series. 13. World Health Organization. ISBN 92-4-159440-3). In the United States, it was estimated that almost 70,000 people were diagnosed with melanoma during 2010 and approximately 9,000 people would be expected to die from the disease (American Cancer Society; www.cancer.org).
Although some conventional cancer therapies have been used in treating metastatic melanoma, they are not effective. Metastatic melanoma therefore remains one of the most difficult cancers to treat and one of the most feared neoplasms. Accordingly, there is a need for new agents and methods for diagnosis and treatment of melanoma.